[Bug rtl-optimization/101523] Huge number of combine attempts

["sarah.kriesch at opensuse dot org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101523

--- Comment #62 from Sarah Julia Kriesch <sarah.kriesch at opensuse dot org> ---
(In reply to Segher Boessenkool from comment #61)
> (In reply to Sarah Julia Kriesch from comment #60)
> > I have to agree with Richard. This problem has been serious for a long time
> > but has been ignored by IBM based on distribution choices.
> 
> What?  What does IBM have to do with this?  Yes, they are my employer, but
> what I decide is best for combine to do is not influenced by them *at all*
> (except some times they want me to spend time doing paid work, distracting
> me from things that really matter, like combine!)
> 
Then, tell other reasons why my requests in the openSUSE bug report have been
rejected in the past, and this bug report has been open for 3 years.
Perhaps it is helpful to know that IBM has fixed memory issues in PostgreSQL
(for openSUSE/upstream) with higher quality via my request with the support for
Red Hat (and faster).

> > Anyway, we want to live within the open source community without any Linux
> > distribution priorities (especially in upstream projects like here).
> 
> No idea what that means either.
> 
There is a reason for founding the Linux Distributions Working Group at the
Open Mainframe Project (equality for all Linux Distributions on s390x).
SUSE, Red Hat and Canonical have been supporting this idea also (especially
based on my own work experience at IBM and the priorities inside).

> > Segher, can you specify the failed test cases? Then, it should be possible
> > to reproduce and improve that all. In such a collaborative way, we can also
> > achieve a solution.
> 
> What failed test cases?  You completely lost me.
> 
This one:
(In reply to Segher Boessenkool from comment #57)
> (In reply to Richard Biener from comment #56)
> PR101523 is a very serious problem, way way way more "P1" than any of the
> "my target was inconvenienced by some bad testcases failing now" "P1"s there
> are now.  Please undo this!

(In reply to Segher Boessenkool from comment #61)
> We used to do the wrong thing in combine.  Now that my fix was reverted, we
> still do.  This should be undone soonish, so that I can commit an actual
> UNCSE
> implementation, which fixes all "regressions" (quotes, because they are not!)
> caused by my previous patch, and does a lot more too.  It also will allow us
> to remove a bunch of other code from combine, speeding up things a lot more
> (things that keep a copy of a set if the dest is used more than once).  There
> has been talk of doing an UNCSE for over twenty years now, so annoying me
> enough to get this done is a good result of this whole thing :-)
Your fixes should also work with upstream code and the used gcc versions in
our/all Linux distributions. I recommend applying tests and merging your fixes
to at least one gcc version.


If you want to watch something about our reasons for creating a collaboration
between Linux distributions (and upstream projects), you should watch my first
presentation "Collaboration instead of Competition":
https://av.tib.eu/media/57010

Hint: The IBM statement came from my former IBM Manager (now your CPO).